Methods are developed for the insertion of acetylcholine receptors and sodium channels into large, solvent-free bilayer vesicles which are studied by chemical, optical, and electrical methods. For the electrical studies, the vesicles are transformed into planar bilayers, separating two aqueous phases. The effects of lipid composition, channel concentration, and ionic environment on the voltage and ligand induced gating characteristics of the reconstituted membranes are determined. Single channel statistics and conductances are determined and receptor desensitization and channel inactivation are studied as a function of lipid composition and protein concentration. The degree of receptor aggregation is measured by fluorescence fluctuation spectroscopy. Attempts are made to separate the receptor subunits from the actual membrane channels and recombine them with the reconstituted channels. The fusion between large vesicles of different lipid composition is investigated by optical and chemical methods and experiments are designed to evaluate the sequence of molecular rearrangments during fusion using electronmicroscopy and fluorescence fluctuation spectroscopy. Mechanical properties of the vesicles such as surface stress, surface compressibility and mechanical breaking strength are measured by direct mechanical manipulation and osmotic gradients.